Changes in numbers of large ovarian follicles, plasma luteinizing hormone and estradiol-17β concentrations and egg production figures in farmed ostriches throughout the year

In this study we described and analysed changes in the numbers of large ovarian follicles (diameter 6.1–9.0 cm) and in the plasma concentrations of luteinizing hormone (LH) and estradiol-17β (E2β) in relation to individual egg production figures of farmed ostriches (Struthio camelus spp.) throughout one year. Ultrasound scanning and blood sampling for plasma hormone analysis were performed in 9 hens on a monthly basis during the breeding season and in two periods of the non-breeding season. Our data demonstrated that: (1) large follicles were detected and LH concentrations were elevated already 1 month before first ovipositions of the egg production season took place; (2) E2β concentrations increased as soon as the egg production season started; (3) numbers of large follicles, LH and E2β concentrations were elevated during the entire egg production season; and that (4) numbers of large follicles, LH and E2β concentrations decreased simultaneous with or following the last ovipositions of the egg production season. By comparing these parameters during the egg production season with their pre-and post-seasonal values, significant differences were found in the numbers of large follicles and E2β concentrations between the pre-seasonal, seasonal and post-seasonal period; while LH concentrations were significantly different between the seasonal and post-seasonal period. In conclusion, our data demonstrate that changes in numbers of large follicles and in concentrations of LH and E2β closely parallel individual egg production figures and provide some new cues that egg production in ostriches is confined to a marked reproductive season. Moreover, our data provide indications that mechanism, initiating, maintaining and terminating the egg production season in farmed breeding ostriches are quite similar to those already known for other seasonal breeding bird species.